Generally, a piping joint structure is provided for piping members (male piping member and female piping member) of a refrigerant cycle system. For example, an insertion portion at an end of the male piping member is inserted into a reception port at an end of the female piping member, while a ring-shaped fixing unit having a circumferential notch is arranged therebetween to axially restrain the male piping member.
In this case, the fixing unit is provided with an arc-shaped protrusion portion, which is inserted in a slot arranged at the reception port of the female piping member. A circular prominent portion is arranged at the insertion portion of the male piping member to be sandwiched between the arc-shaped protrusion portion and a reception surface of the female piping member. Thus, the male piping member is restricted from being disengaging from the female piping member.
However, in this case, the fixing unit is to contact the male and female piping members in a fixed right-left direction, otherwise the male piping member fails to be connected with the female piping member or a gap is caused therebetween.